The present invention relates to a method and apparatus for recording keyboard music for re-creation on a similar keyboard instrument by actuation of the keys and, more particularly, to the provision of means for stretching the recorded notes before recording and playback on electronic keyboard instruments. As disclosed in Vincent U.S. Pat. No. 3,905,267, and Englund U.S. Pat. No. 3,604,299, digitally recorded key switch actuations are stretched by pulse stretching circuitry subsequent to the recording on magnetic tape and requires a pulse stretcher for each note of the keyboard.
In accordance with the present invention, the frames of key switch actuations, the key data from a key switch multiplexer, are applied to a pair of serially connected 128-bit shift registers. The output of the first shift register is supplied to the second shift register and to an OR gate along with the output of the second shift register so that every key switch closure or actuation extends over two time frames and is, in effect, a note stretcher. This note stretching removes the very sharp and mechanical sound from short notes.